The majority of ophthalmic surgery is now done under local anesthesia, most of which is administered by peribulbar or retrobulbar injection. The three main objectives of a peribulbar anesthetic block are: loss of pain sensory function, loss of motor function, and globe softness. A failure to obtain a satisfactory anesthetic block, therefore, will result in pain and discomfort to the patient and a more difficult labor for the surgeon. In actual practice, when the practitioner has an assistant at hand to assist with the anesthetic, the block success rate at meeting the above objectives may be improved by the judicious application of digital pressure to the lower lid at the injection site. This action prevents the anesthetic from spreading throughout the lower lid tissue, instead directing it rearward, into the peribulbar space, where the desired effects are obtained. In most practice settings, the luxury of having an assistant who is experienced at this technique is not available. To attempt this maneuver with just two hands is to sacrifice the needle stability in the hand of the operator. This would increase the risk of globe perforation, hemorrhage, and other possible complications known to occur with this type of anesthesia.
Current practice in retrobulbar anesthesia involves the use of a 11/2 inch needle and typical anesthetic volumes of about 3-5 cc. Peribulbar anesthesia typically involves the use of a 1 inch needle with volumes of 6-10 cc. The longer needle used in retrobulbar anesthesia increases the risks of retrobulbar hemorrhage and nerve injury since the intraorbital neurovascular structures tend to become less mobile the further back into the orbit they are located. The shorter needle of the peribulbar method of anesthetic block is favored in this respect; however, the disadvantage with it is the higher volume of anesthetic required and the lower success rate since the effectiveness of the block is directly dependent upon the favorable spread of the anesthetic. The higher volume of anesthetic increases the chances of forward diffusion of the anesthetic, leading to swelling of the conjunctiva which interferes with the surgical field, making the operation more difficult.
A new device is herein disclosed which alleviates the awkwardness and difficulty of administering the local anesthetic into the peribulbar area of the eye and, assures the proper distribution of the anesthetic throughout the peribulbar space. The device is especially useful when the administrator of the block has no assistance available. The invention has the additional advantage of reducing the amount of anesthesia necessary. A peribulbar block can be done effectively with the disclosed device using a lower dose previously only used in increased risk retrobulbar anesthesia procedures. Moreover, it is possible to effectively use a shorter needle with the present invention, thereby increasing safety to the patient.